1. Field of the Invention
This invention pertains to a switching arrangement for operating electrical devices wherein a switching arrangement and the noted devices are connected with each other via a communication line.
2. Discussion of the Background of the Invention and Material Information
Electrical devices in the communications field or in additional fields of application are utilized in daily operation often for only short time periods. Nevertheless, these devices normally remain in an uninterrupted functional state, thus wasting valuable energy. Particularly in battery operated devices this loss of energy is particularly disadvantageous. European patent document EP-OS 0 417 425 describes a telephone network which includes several subscriber stations or terminal devices which can be quickly activated and inactivated as well as being connectable onto further networks.
It is also known from European patent document EP-OS 0 417 542 that terminal devices can, at desired locations, be inductively coupled onto a two wire conductor. For such flexible networks with selectively coupleable terminal devices, in order to maintain the mobility thereof, preferably current sources comprised of batteries are provided. In case the terminal units, which in the customary manner are constantly in a functional state, this results in a short life span of the batteries, increased interruptions in the telephone network and thus leads to increased operating costs. European patent document EP-OS 0 361 350 pertains to a mobile telephone station which is connected with a base station and also includes an energy saving circuit, whose transmitting unit, during the so-called stand-by-mode, or in its dormant state is shut off, in order to reduce the power requirements of the telephone station. Via a control signal, transmitted from the base station, the telephone station is again activated, upon demand. The control signal is subdivided into differing areas, via which the telephone station is brought to stand-by and in any case is induced to send out a confirmation signal.
The disadvantage of this energy saving circuit is that for the monitoring of the control signal, with the exception of the sending unit, practically all significant circuit blocks of the telephone station have to be in their normal operating mode. Particularly, the reception and control portions are required for the detection of the coded control signals. In addition, the energy saving circuit is only usable in case the predetermined transfer channel between the base station and telephone channel does not have to carry additional useful signals or interfering signals.